Emerging (per)fluorinated compounds in the watercycle

Perfluoroalkyl sustances (PFAS) have recently gained interest of the water companies because of their persistence in the environment and their occurrence in sources of drinking water. Both perfluoro octanoic acid (PFOA) and perfluoro octane sulfonic acid (PFOS) are notorious because of their occurrence, and are poorly removed from the drinking water production chain by conventional purification processes. Recent studies have shown that substitutes of PFOA, such as HFPO-DA (FRD-903, constituent of GenX) have been observed in locations where PFOA has been previously reported to be present in surface water. FOSA is another PFAS frequently reported to be present in surface waters, which is not included in regular monitoring programs in the Netherlands. A third relatively poorly known PFAS is the polar trifluoromethanesulfonic acid (F3-MSA), which has been recently observed in several locations in Europe up to 1 µg/L. The occurrence of these relatively new PFAS in the watercycle initiated the present study.
In the present study analytical methodologies were developed for F3-MSA, HFPO-DA, and FOSA in order to determine the occurrence of these PFAS in the watercycle, by means of a sampling campaign. A reversed phase C18 LC-MS/MS method was developed for FOSA by UVA-IBED, yielding satisfactory LOD and LOQ results. For the polar F3-MSA and HFPO a mixed-mode and a reversed phase C18 method were developed, respectively, using a high resolution Orbitrap Fusion mass spectrometer for detection, yielding satisfactory LOD and LOQ results for both F3-MSA and HFPO-DA.